package com.likou.written.shenzhou;

import java.util.Scanner;

/**
 * Author: 陈桂明
 * Date: 2025/10/9 17:26
 * Description: shenzhou2
 */
public class shenzhou2 {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        // // 注意 hasNext 和 hasNextLine 的区别
        // while (in.hasNextInt()) { // 注意 while 处理多个 case
        //     int a = in.nextInt();
        //     int b = in.nextInt();
        //     System.out.println(a + b);
        // }

        Long n = in.nextLong();
        System.out.println(4 * n);

    }
}
